"In Science the authority embodied in the opinion of thousands is not worth a spark of reason in one man." - Galileo Galilei

Saturday, January 29, 2011

On Taubes and Toilets

One of our toilets has been acting balky lately. Last night I went to flush it and nothing happened. I started pondering on the possible causes of this, and had a brief vision of a bunch of Ph.D's standing around, stroking their chins and sagely examining the toilet through glasses perched on the ends of their noses. After a few knowing glances at each other, they pronounced: "From the First Law of Thermodynamics, we know the problem with your toilet is that, at some point in the past, less water came in than left!"

Maybe I should have skipped that last martini at dinner last night.

Anyway, my imaginary colleagues were only acting as scientists often do, pronouncing "truth" without getting to the root cause of the issue. Or perhaps my subconscious has been imprinted from too many conversations like this with my children:

Me: "How did you get so dirty?"Child: "I was playing in dirt."

Back to the toilet. My imaginary scientist friends, while technically correct, were (as scientists often are) totally unhelpful. If I were to fix my toilet, I would need to know how it works, particularly the possible failure modes. In other words, I need to get to the root cause of why it didn't flush. Once I know what's actually broken, I can fix it. Invoking the First Law of Thermodynamics might make one sound smart, but it doesn't get my toilet flushing again. And believe me, in this case it was a vital importance to identify and repair the root cause, posthaste.

The toilet is actually an example of a self-regulating system, by which I mean that when it works correctly, I don't have to pay attention to it. If you're not familiar with the workings of the common toilet, check out this entry at HowStuffWorks.com. Basically, there's some clever gadgets in there that make sure things go smoothly. When you push the handle down, it pulls up the flapper, basically a rubber stopper with a hole in the bottom. There's air inside the stopper, which causes it to float open as long as the water level is above the stopper. Once the water is gone, the stopper closes. That's the output side. The input side is controlled by a float-activated valve. When the water level falls, so does the float, which opens the valve and lets water into the tank. As the tank fills, the float rises until it hits the switch and shuts the valve, turning off the water. This whole setup is basically tuned to ensure that you have enough water leaving the tank at the proper rate to get a good flush, while not having too much water enter the tank and thus flooding your bathroom. The toilet has an additional fail-safe to avoid the latter fate, in the form of an overflow pipe. If your float switch doesn't work, then the water goes down the overflow pipe instead of all over your floor.

My particular problem was too little water, not too much. Since I have confidence in the First Law of Thermodynamics (at least in approximately flat regions of spacetime, like my bathroom), I know that something caused the tank to not fill. The water didn't fill the tank at some point then magically vanish. One possibility was that my water main had broken. Checked the sink faucet, plenty of water there. Rather than stand around and be mystified by the inner workings of my toilet, I opened it up and took a look inside. No water alright, and it looked like the float was stuck. A quick poke and the toilet started filling. The moral of the story is that the laws of physics don't tell you how things work, but rather the constraints under which they work (e.g. the amount of water leaving the toilet in a flush is the same as the amount that entered when it filled). To solve my problem I needed to understand the mechanism by which the toilet regulated water flow and level, and how that regulation could go wrong. In other words, if you know what causes the toilet to work correctly, then you can infer what might cause it work incorrectly, and take appropriate action.

If you've read Gary Taubes most recent work, Why We Get Fat, you probably have realized by now that my toilet story is a bit of a setup. Why We Get Fat (WWGF) is generally described as "Good Calories, Bad Calories" lite, but it is a bit more than that. Taubes has focused on obesity in particular, and honed his arguments and presentation, and brought in some more recent research as well. It's an excellent and fast-paced read, and I highly recommend it.

The key hypothesis of WWGF in terms of obesity is the same as GCBC: that obesity is the result of a failure in the regulation of metabolism, specifically carbohydrate metabolism. A broad set of critics attack both GCBC and WWGF on various detailed points, while missing the big picture. For instance, there's much ado about the specifics of Taubes' hypothesis on how this failure in carbohydrate metabolism arises. Taubes posits that overconsumption of carbohydrates basically leads to insulin resistance (though notes that the situation may not be so simple), while others point to various evidence that it may be specific carbohydrates (fructose), or vegetable oil, lack of physical activity, etc. These make for nice academic discussions, but if you're one of the millions of people with a broken metabolism, none of this is very helpful. Much as was the case with me and my toilet, if you're going to fix your metabolic machine, you need to have some idea of how it works and what might be go wrong. WWGF is a great place to start educating yourself, provided you don't fall in the trap of running around screaming "I can't see the forest because I've got blood in my eyes from running into all of these damned trees!"

The publication of WWGF has also revived the strident preaching from the members of the Holy Church of the First Law of Thermodynamics. Now, I'll give you a pass if you read GCBC and perhaps came away thinking that Taubes implied that low carbohydrate diets somehow got around energy conservation. GCBC was a dense book, and Taubes (who was a degree in physics) no doubt thought that the First Law was just generally held to be true and that nobody would question his belief in it, and so didn't focus on it much. Taubes clearly learned the hard way that you can't take these things for granted. WWGF has two chapters on this topic, and makes it very clear that 1) Yes, Virginia, the First Law of Thermodynamics is alive and kicking, but 2) that the First Law adds no information as to the cause of obesity, or what you might do to fix it. If you read WWGF and still think Taubes is claiming that thermodynamics doesn't apply to biological organisms, then you either didn't really read the book, weren't paying any attention, or have the logical facilities of a monkey on crack.

The real lesson of WWGF is the same as my toilet story: just knowing the constraints on the workings of your body (e.g. conservation of energy) is not the same as knowing how the pieces actually fit together, the cause-effect relationships that make the whole machine go. You can't fix something without having some idea of how it works, whether it is a toilet or the human body. Like my toilet, your metabolism (and that of all living organisms) is self-regulating. Humans seem to be control-freaks in general, and we think that every aspect of life needs constant attention, much like driving a car (I wish people paid as much attention to driving as they do to other less consequential things, like whether or not their children poop enough times a day). But when my toilet works right, I don't have to sit in the bathroom and monitor it, waiting to shut off the water if there's an overflow, or fiddling with the float valve switch. It just does it's thing. Metabolism is the same way. Energy regulation is the key aspect of life, from bacteria to humans, and most life doesn't have the capacity to fret about how many calories it ate or how much it exercised. If your metabolism is operating correctly, by definition it is impossible to eat too much. When you have too much energy stored, the body has ways of eliciting biochemistry and behavior (which is just complicated biochemistry) to bring things back into balance: appetite is decreased, thermogenesis is increased, you have the urge to move around, etc.

If you're obese, you don't have a character or mental defect any more than my balky toilet does. You have a physical problem in metabolic regulation. Invoking the First Law of Thermodynamics and berating obese people as having a behavioral issue does not address the root cause of obesity, any more than a similar approach would have worked in fixing my toilet (I'm having visions of registered dieticians bitching out my commode for lack of self-control). WWGF is a great place to start "opening the box" and empowering yourself to start giving the "experts" the finger, stop feeling like a failure because your experience doesn't agree with their beliefs, and get down to actually solving the problem.

Personally I would not read a GCBC Light. I want Heavy. I want to be told how La Magnen's rats spaced out their meals and amounts eaten so that it matched fuel usage while they slept. This has has to be as interesting a narrative as the rise and fall of the "volatility smile" on Wall Street.

Good job on this. My own take on the obesity epidemic is that the concern is misplaced. To suggest obesity "causes" other problems that result in debility and early death is like saying that the smoke that accompanies a forest fire damages trees and causes many of them to die. Scientists should focus on the major factors that cause chronic inflammatory disease, excessive fructose and omega-6 intake.

I sort of thought the same thing. I really enjoyed the density of GCBC as well, and thought I'd find the "popular" version a bit boring. But it was quite the engaging read, a testament to Taubes' skill as a writer. Worth at least a trip to the library, I read it in a few hours.

@David Brown:

Agreed. I vaguely remember some PBS-sh show (Connections?) which discussed the origin of modern medicine, I think basically battlefield medicine during the Crimean (?) war. Prior to that things were very different. Anyway, the whole point of triage is to treat the symptoms directly. Obviously if you're bleeding heavily, the cause of the bleeding matters less than stopping it. I believe this attitude persists in modern medicine, where many treatments are aimed at alleviating symptoms rather than dealing with an underlying cause. Obesity is just a symptom (sometimes) of an underlying metabolic disturbance. The way obesity is generally treated is tantamount to me hauling buckets of water into my bathroom to fill the toilet. It fixes the symptom, but not the root cause, and if I continued in this manner I'd be doomed to dragging water to the toilet for the rest of my life.

Great post. However you say in several places that Taube's thesis is that obesity is caused by an imbalance in carbohydrate metabolism, when it is really about an imbalance in FAT metabolism and regulation. Excesive consumption of refined carbohydrates drives insulin which drives FAT accumulation. So anything that increases insulin will have the same effect on fat metabolism..Carbohydrates are just the main drivers in the imbalance ...

I know what you're saying. It may be better to say there is an imbalance in energy metabolism in general. For instance, if you are leptin resistant (arguably falls on the fat side instead of carb), then one can see how eating carbohydrates leads to bad stuff. On the other hand, your problem may be that you secrete too much insulin in response to a given carbohydrate load, which knocks your blood sugar out of balance, and so forth.

Following David Brown's point, obesity is often categorized as "a multi-factorial, complex disease", but this assessment is off if obesity is just a symptom. It may be a symptom that arises from different root causes, and focusing on obesity just confuses things. There are skinny people with metabolic syndrome, for instance, and obese people with excellent blood sugar control. The Aztecs left fairly detailed medical records, with many terms describing different kinds of obesity, but did not describe diabetes. While the connection between insulin and storage/release of fat in adipocytes is fairly straightforward, the overall regulation of energy intake/output/storage is more complex, and could fail at several different points, much as there was more than one possible cause for my toilet tank to be empty.

@Bill, the ancient Romans used toilets like we have, so the last link you posted is inaccurate. I've seen the ruins personally. They were public toilets, a stone bench with multiple holes along it. No privacy at all LOL

I've also seen the same type of toilet, a stone box with a hole in it in medieval fortresses.

Wow, I've had a simplified expalnation of heparin given to me with pop-beads for an illustration. And I've often had to simplfy science by comparing it to an ant-hill, etc, so I could grasp it better. But never a toilet. You get an A for creativity. A toilet would also work well for explaining politics, how versatile!

Thanks for the post! I tried to get thru GCBC and just could not do it, as much as I wanted to. So I am thankful to a "lighter" version. My husband read a paragraph I shared from WWGF and said "Man, he needs to get to the point". I just laughed, that is him getting to the point!

quote: "This also makes clear that there is no inconsistency between hormonal control theories and “calories in, calories out”. They both move in concert, but the hormones are the horse and the calories are the cart, not the other way around."

Nice post but JorgeA you have it backwards, the lack of metabolism on the carbs produces Fat after the fact. That newly depositeed fat in cells is not what need to be used. It is another issue dealing with the Fat cells but it isa the carbs that needs started it all when there is a metabolic inbalance.

Gary only mentions leptin once in the prologue to GC, BC, and not at all in WWGF, as far as I can see. In a relatively recent podcast, he was asked about it specifically, and said that any leptin effects were "downstream of insulin", i.e. it's insulin we still have to worry about.

However, there are a few vocal people out there who take the opposite view.

However, of those I've read, I'm not seeing a clear picture of what, for example, might lead to leptin resistance, and how the biological mechanism might work.

So it would be good to have your take on leptin, perhaps in some future article, if you have a take on it that is.

Re: being confused about leptin (and the orchestration of nutrition and metabolism in general): you've got plenty of good company. This is a cutting-edge research topic. The question that is perhaps most relevant here is leptin's role in the *development* of metabolic syndrome, and of course how nutrition and other environmental factors might play a causative role. The current thinking seems to be that leptin resistance actually precedes insulin resistance. That actually adds a useful piece to the hormonal hypothesis: since leptin is key in controlling appetite, leptin resistance could lead to overeating, hyperinsulinemia, and so forth.

But for those suffering from metabolic syndrome, the relevant question is what to do about it? The one thing that seems clear is that once you've broken the machine, the best *known* fix is to control insulin levels. I don't think we know how to fiddle leptin levels or sensitivity, and indeed much of metabolic regulation is probably out of our direct influence (at least without drug interventions). But the one thing you definitely can control is your insulin through carbohydrate restriction.

And if there's one lesson I've learned in my studies of metabolic regulation, it's that everything is connected. If increasing A increases B, then increasing B often also increases A, as the body attempts to maintain allostasis. This isn't always true, but I wouldn't be surprised if reigning in hyperinsulinemia also had a positive effect on leptin metabolism. But we'll have to wait for the research to really know.

In support of your last paragraph, one fairly prominent leptin enthusiast prescribes cutting down carbs to something like Atkins induction levels in order to tackle leptin resistance. Of course this will also tend to reduce insulin levels as well, so maybe insulin is still "the guv'nor" (as they say in London) after all, and Gary (and Dr Atkins, and just about every low-carb prophet since William Banting) is still basically right, even if there is more going on under the covers than are dreamt of in their philosophy.